unfair Rental car insurance - Dollar rental insurance

We rented a car in Germany. Orbitz sold at the same time Allianz insurance. We bought that. But when we came to Stuttgart, Dollar told us that they do not accept that insurance, nor our credit card rental car insurance. We HAD to buy the dollar insurance. Consequence: twice the price. We would have never booked through Orbitz if you would have disclosed the full price, since there are cheaper options. Fraudulent to say the least. Especially since Dollar told us that Orbitz knows. Of course customer relations told us that we should have read the small print of the Dollar contract. I bet you would be furious if someone would do this to you.